Sheaffer has upgraded its ink cartridge design for improved functionality - delivering better color identification and transportability. The color of the cartridge is now the same as the ink, making it much easier to identify the color of ink inside. ForJet Black, Blue, and Blue-Black the cartridges remain transparent but now they have an end cap which clearly identifies the ink color. This new feature still lets consumers easily see the level of ink in the cartridge. In addition, the new cartridges arenow transportable. This is possible as the new cartridges can only be pierced on one end. This allows a traveler to carry an un-pierced cartridge in a fountain pen chamber, without the risk of leakage during transportation, and especially during air travel - a common concern among fountain pen aficionados. 5 per pack, compatible with White Dot Classic, Cartridge, and Calligraphy pens. These are the refills for the Sheaffer Calligraphy Classic Kit .